The primary cause of death and illness related to Parkinson's Disease (PD) is respiratory infection or obstruction resulting from a general failure to effectively cough to protect the airway. Individuals with PD exhibit substantial difficulty generating sufficient respiratory driving pressure and vocal fold closure to generate a strong effective cough, and are generally unaware of their airway deficits, suggesting that these deficits may be related to impaired sensory function. We previously confirmed this suggestion and demonstrated significant laryngeal somatosensory deficits in individuals with PD compared with healthy controls. However, medical and neurosurgical interventions remain inadequate, leaving most PD patients without access to an appropriate, evidence-based intervention to improve airway protection. The current standard of care for improving speech and voice in PD is intensive voice therapy (IVT), also known as Lee Silverman voice treatment. The increased motor and sensory experience accompanying increased respiratory pressure, vocal fold closure, and voice loudness, and the particular focus on increased sensory self-awareness in IVT may yield important benefits to the ability to detect and effectively cough to expel a substance from invading the airway. However, the effects of IVT on laryngeal sensory function and other mechanisms of airway protection are unknown. Our preliminary experiments demonstrated improved voice and airway function, including increased strength and speed of cough that approximated normal function following IVT. These improvements have great potential to improve health and quality of life, and to increase independence of individuals with PD. Therefore, we will test the hypothesis that IVT will result in improved cough, breathing, and airway sensory function in individuals with moderately severe PD. The proposed research has 3 specific aims. In Aim 1, we will test the hypothesis that IVT will improve the efficiency of air intake in preparation for a cough, and the ability to strongly and efficiently expel air for removal of a substance from invading the airway. This aim is innovative, clinically relevant, and will determine the impact of IVT on the efficiency and strength of cough in PD. In Aim 2, we will test the hypothesis that IVT will improve the ability of individuals with PD to efficiently access and move lung air volume and to generate respiratory driving pressures. This aim is innovative, important, and will assess the underlying capacity of the respiratory mechanism available for airway protection. These measures also enable us to account for underlying covariates in pulmonary function that may impact cough. In Aim 3, we will use an endoscopic assessment device developed in our laboratory to test the hypothesis that IVT will improve laryngeal sensory function. This aim is highly innovative, clinically relevant, and will directly assess the ability of the larynx to detect and respond to a sensory stimulus. In this work, we will develop a more comprehensive view of airway sensorimotor control, how a rehabilitative strategy such as IVT impacts these functions in a neurodegenerative disease, and how sensory changes correlate with breathing, cough, and voice. PUBLIC HEALTH RELEVANCE: Parkinson's Disease (PD) afflicts more than two million individuals in the United States, and more than seven million worldwide, leading to a total annual cost of PD in the United States of about $38 billion, and an estimated annual cost to society of as much as $6,000 per capita. Given that the vast majority of individuals with PD may eventually experience increased risk of illness or death due to an increasing failure to protect the airway and that most currently do not have access to an appropriate, evidence- based intervention to improve airway function, the purpose of this study is to examine the effects of an intensive voice therapy program on mechanisms of airway protection including cough, breathing, and airway sensory function. Results from the proposed study may have great potential to improve health and quality of life, to decrease individual and societal health care costs, to increase independence of individuals with PD, and to inform our understanding of the mechanisms of airway sensorimotor control, with important implications for aging and other neurological disease.